JP2013187419A - Photoelectric conversion element and solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a solar cell having higher conversion efficiency by providing a new photoelectric conversion element material.SOLUTION: A photoelectric conversion element includes a pair of electrodes (102, 106) and an active layer (104) existing between the electrodes and also includes a layer containing a benzodipyrrole compound represented by general formula (I) between the active layer (104) and one of the electrodes (102, 106).

Description

  The present invention relates to a photoelectric conversion element and a solar cell module.

  In recent years, solar cells including photoelectric conversion elements using organic materials have been developed. Such a photoelectric conversion element can be manufactured with less energy and can be relatively easily increased in area.

  A photoelectric conversion element usually has an active layer and an electrode where light absorption is performed. In order to efficiently transport carriers generated in the active layer to the electrode and improve photoelectric conversion efficiency, the photoelectric conversion element is provided between the electrode and the active layer. A technique for providing a buffer layer on the substrate is known. For example, Non-Patent Document 1 describes an example in which poly (3,4-ethylenedioxythiophene) -poly (styrenesulfonic acid) (PEDOT: PSS), which is a conductive polymer, is used as a material for the buffer layer. . Non-Patent Document 2 describes an example in which molybdenum trioxide is used as the material of the buffer layer.

S. E. Shaheen et al. Appl. Phys. Lett. 78, 841-843, 2001. V. Shrotria et al. Appl. Phys. Lett. 88, 073508, 2006.

  In order to further increase the efficiency of photoelectric conversion elements, further photoelectric conversion element materials are required. For example, the conversion efficiency can be improved by making the buffer layer as uniform and transparent as possible. However, PEDOT: PSS has a problem in uniformity because it is formed using a particle-dispersed coating solution, and has a short wavelength visible. There was a problem of absorbing light. Also, molybdenum trioxide has a problem that the conversion efficiency greatly depends on the film thickness.

  An object of the present invention is to provide a new photoelectric conversion element material and to realize a solar cell having higher conversion efficiency.

  As a result of intensive studies by the present inventors, a compound having a benzodipyrrole skeleton can be used as a photoelectric conversion element material, and by providing a layer containing a compound having a benzodipyrrole skeleton between an electrode and an active layer The inventors have found that the conversion efficiency of the photoelectric conversion element is improved, and have reached the present invention. That is, the gist of the present invention is as follows.

（式（Ｉ）中、Ｘ^１とＸ^２との一方は置換基Ｒ^２を有する窒素原子であり、他方は置換基Ａｒ^３を有する炭素原子であり、Ｒ^１〜Ｒ^４はそれぞれ独立に１価の有機基を表し、Ａｒ^１〜Ａｒ^４はそれぞれ独立に、置換基を有していてもよい芳香族基を表す。）
［２］前記ベンゾジピロール化合物を含有する層は、前記電極の一方である陽極と前記活性層との間に設けられていることを特徴とする、［１］に記載の光電変換素子。
［３］前記ベンゾジピロール化合物を含有する層がさらに電子受容性化合物を含有することを特徴とする、［２］に記載の光電変換素子。
［４］前記電子受容性化合物の電子親和力が４ｅＶ以上７ｅＶ以下であることを特徴とする、［３］に記載の光電変換素子。
［５］太陽電池であることを特徴とする、［１］から［４］のいずれかに記載の光電変換素子。
［６］［５］に記載の光電変換素子を備えることを特徴とする、太陽電池モジュール。 [1] A photoelectric conversion element having a pair of electrodes and an active layer present between the electrodes,
A photoelectric conversion element comprising a layer containing a benzodipyrrole compound represented by the following general formula (I) between the active layer and one of the electrodes.

(In formula (I), ^one of X ¹ and X ² is a nitrogen atom having substituent R ² , the other is a carbon atom having substituent Ar ³ , and R ^{1 to} R ⁴ are each independently 1. A valent organic group, and Ar ^{1 to} Ar ⁴ each independently represents an aromatic group which may have a substituent.)
[2] The photoelectric conversion element according to [1], wherein the layer containing the benzodipyrrole compound is provided between an anode which is one of the electrodes and the active layer.
[3] The photoelectric conversion element according to [2], wherein the layer containing the benzodipyrrole compound further contains an electron accepting compound.
[4] The photoelectric conversion element according to [3], wherein the electron accepting compound has an electron affinity of 4 eV or more and 7 eV or less.
[5] The photoelectric conversion element according to any one of [1] to [4], which is a solar cell.
[6] A solar cell module comprising the photoelectric conversion element according to [5].

  A new photoelectric conversion element material can be provided, and a solar cell with higher conversion efficiency can be realized.

It is a schematic cross section of the photoelectric conversion element which concerns on 1st Embodiment. It is a schematic cross section of the photoelectric conversion element which concerns on 2nd Embodiment. It is a schematic cross section of the photoelectric conversion element which concerns on 3rd Embodiment. It is a schematic cross section of the solar cell as one embodiment concerning the present invention. It is a schematic cross section of the solar cell module as one embodiment concerning the present invention.

  Hereinafter, the photoelectric conversion element according to each embodiment of the present invention will be described in detail with reference to the drawings. The embodiments described below are merely exemplary embodiments (representative examples) of the present invention, and the present invention is not limited to the following embodiments.

<1. Photoelectric conversion element>
The photoelectric conversion element according to the present invention has a pair of electrodes and an active layer existing between the electrodes, and is represented by a general formula (I) described later between the active layer and at least one of the electrodes. A layer containing a benzodipyrrole compound. The layer containing the benzodipyrrole compound is preferably a buffer layer, and more preferably an anode buffer layer. Several embodiments of the photoelectric conversion element according to the present invention will be described below.

  The photoelectric conversion elements according to the first to third embodiments of the present invention include a substrate 101, an electrode 102, a buffer layer 103, an active layer 104, a buffer layer 105, and an electrode 106, as shown in FIGS. . The active layer 104 of the photoelectric conversion element according to the first embodiment includes an active layer (i-layer) 104c. The active layer 104 of the photoelectric conversion element according to the second embodiment includes an active layer (p-layer) 104a and an active layer (n-layer) 104b. The active layer 104 of the photoelectric conversion element according to the third embodiment includes an active layer (p-layer) 104a, an active layer (i-layer) 104c, and an active layer (n-layer) 104b.

  In the photoelectric conversion element according to another embodiment of the present invention, the substrate 101 is disposed on the electrode 106 side instead of the electrode 102 side. That is, the photoelectric conversion element according to another embodiment has a structure in which the electrode 102, the buffer layer 103, the active layer 104, the buffer layer 105, the electrode 106, and the substrate 101 are stacked.

  The photoelectric conversion element according to a further embodiment of the present invention includes the electrode 102, the active layer 104, the electrode 106, and at least one of the buffer layer 103 and the buffer layer 105. Here, at least one of the buffer layer 103 and the buffer layer 105 included in the photoelectric conversion element according to another embodiment of the present invention is a layer containing a benzodipyrrole compound represented by the general formula (I). As described above, the photoelectric conversion element according to the present invention may not include the substrate 101, and may not include one of the buffer layer 103 and the buffer layer 105. Further, the light receiving surface of the photoelectric conversion element may be on the electrode 102 side or on the electrode 106 side.

  Hereinafter, each of the above-described layers will be described in detail.

<1.1 Substrate (101)>
The substrate 101 serves as a support for the photoelectric conversion element. There is no particular limitation on the material of the substrate 101, but when the substrate 101 is on the light-receiving surface side of the photoelectric conversion element, it is preferable to use a highly light-transmitting material for the substrate 101. As the substrate 101, a colored one or a colorless one can be used. As a specific example of the substrate 101, a quartz or glass plate, a plastic film, a sheet, or the like is used. In particular, the use of a glass plate as the substrate 101 is preferable in terms of strength. In addition, it is preferable in terms of lightness to use a transparent synthetic resin substrate such as polyester, polymethacrylate, polycarbonate, or polysulfone as the substrate 101. The substrate 101 may have a multilayer structure including a plurality of layers.

  The substrate 101 preferably has a high barrier property. Here, the barrier property refers to the ability to block a gas such as oxygen or water vapor. When the gas barrier property of the substrate 101 is low, the photoelectric conversion element may be deteriorated by a gas passing through the substrate 101. When a synthetic resin substrate is used as the substrate 101, for example, by providing a dense silicon oxide film or the like on one surface or both surfaces of the synthetic resin substrate, the gas barrier property of the substrate 101 can be improved.

<1.2 Electrodes (102, 106)>
The electrodes 102 and 106 are terminals for taking out electricity generated by the photoelectric conversion element from the outside. One of the electrodes 102 and 106 is an anode (an electrode for collecting holes, an anode), and the other is a cathode (an electrode for collecting electrons, a cathode). In the following description, it is assumed that the electrode 102 is an anode and the electrode 106 is a cathode. However, the electrode 102 may be a cathode and the electrode 106 may be an anode. It is preferable that the electrode located in the light-receiving surface side of a photoelectric conversion element has translucency.

[1.2.1 Anode (102)]
The anode 102 collects holes that are photocarriers generated in the active layer 104. The material of the anode 102 is not particularly limited, and may be composed of, for example, a metal oxide such as indium tin oxide or indium zinc oxide. The anode 102 can be formed by, for example, a coating method such as a spin coating method, a sputtering method, a vacuum evaporation method, or the like.

  When the anode 102 is located on the light receiving surface side of the photoelectric conversion element, from the viewpoint of improving the photoelectric conversion efficiency, the transmittance of visible light (light having a wavelength of 360 to 830 nm) of the anode 102 is preferably 60% or more, More preferably, it is 80% or more. The thickness of the anode 102 is not particularly limited, but is preferably 10 nm or more, and more preferably 50 nm or more from the viewpoint of strength. On the other hand, from the viewpoint of lightness, it is preferably 1000 nm or less, and more preferably 300 nm or less. The anode 102 may be colored or colorless.

[1.2.2 Cathode (106)]
The cathode 106 collects electrons that are photocarriers generated in the active layer 104. The material of the cathode 106 is not particularly limited. For example, a metal or alloy such as magnesium, indium, calcium, aluminum, or silver, or a transparent oxide semiconductor such as indium tin oxide or indium zinc oxide is used. This is preferable because electrons generated by charge separation in the active layer 104 can be efficiently received. The cathode 106 can be formed by, for example, a coating method such as a spin coating method, a sputtering method, a vacuum evaporation method, or the like.

  When the cathode 106 is located on the light receiving surface side of the photoelectric conversion element, from the viewpoint of improving the photoelectric conversion efficiency, the transmittance of visible light (light having a wavelength of 360 to 830 nm) of the cathode 106 is preferably 60% or more, More preferably, it is 80% or more. The thickness of the cathode 106 is not particularly limited, but is preferably 10 nm or more, and more preferably 50 nm or more from the viewpoint of strength. On the other hand, from the viewpoint of lightness, it is preferably 1000 nm or less, and more preferably 300 nm or less. The cathode 106 may be colored or colorless.

<1.3 Buffer layer (103, 105)>
The buffer layers 103 and 105 are for efficiently transporting carriers (electrons or holes) generated by charge separation in the active layer 104 to the electrodes 102 and 106. In this specification, the buffer layer that transports holes to the anode is referred to as an anode buffer layer. A buffer layer that transports electrons to the cathode is called a cathode buffer layer. Usually, the anode buffer layer is in contact with the active layer and the anode, and the cathode buffer layer is in contact with the active layer and the cathode.

  Thus, the buffer layer is disposed between the active layer 104 and one of the electrodes (102 or 106). In one embodiment of the present invention, the buffer layer disposed between the active layer 104 and one of the electrodes (102 or 106) contains a benzodipyrrole compound represented by the following general formula (I). Yes. As described above, the photoelectric conversion element according to the embodiment of the present invention has at least one of the buffer layer 103 and the buffer layer 105. Hereinafter, the photoelectric conversion element will be described as having both buffer layers. .

  Hereinafter, the anode buffer layer and the cathode buffer layer will be described in more detail. In the following description, it is assumed that the electrode 102 is an anode and the electrode 106 is a cathode. That is, in this case, the buffer layer 103 is an anode buffer layer, and the buffer layer 105 is a cathode buffer layer. Moreover, the benzodipyrrole compound represented by general formula (I) mentioned later is suitable as an anode buffer layer material, and it demonstrates below that the anode buffer layer 103 contains a benzodipyrrole compound.

[1.3.1 Anode buffer layer (103)]
The anode buffer layer 103 contains a benzodipyrrole compound represented by the following general formula (I). Hereinafter, the benzodipyrrole compound represented by the general formula (I) is referred to as a benzodipyrrole compound of the present invention.

In formula (I), one of X ¹ and X ² is a nitrogen atom having a substituent R ² , and the other is a carbon atom having a substituent Ar ³ . In formula (I), two bonds indicated by broken lines represent that one is a single bond and the other is a double bond. More specifically, the bond between the nitrogen atom having the substituent R ² and the carbon atom having the substituent Ar ⁴ is a single bond, and the carbon atom having the substituent Ar ³ and the carbon having the substituent Ar ⁴ The bond between the atoms is a double bond.

  The molecular weight of the benzodipyrrole compound of the present invention is not particularly limited as long as a layer can be formed between the electrode and the active layer of the photoelectric conversion device according to the present invention, and is usually 460 or more, preferably 500 or more, more preferably 600 or more. In general, it is 5000 or less, preferably 4000 or less, more preferably 3000 or less. When the layer is formed by vapor deposition, 2000 or less is preferable.

In the formula (I), R ¹ and R ² each independently represents a monovalent organic group. Examples of monovalent organic groups include a hydrogen atom; a halogen atom such as a fluorine atom or a chlorine atom; an alkyl group having 1 to 30 carbon atoms such as a methyl group or an ethyl group; a carbon having a sulfonic acid or a sulfonate group at the terminal. An alkyl group having 1 to 30 carbon atoms; an alkyl group having 1 to 30 carbon atoms having a phosphate group or a phosphate group at a terminal; an alkyl group having 1 to 30 carbon atoms having an alkyl ammonium group at a terminal; an aralkyl group such as a benzyl group; An alkenyl group such as a vinyl group; an acyl group; an alkoxy group having 1 to 30 carbon atoms such as a methoxy group or an ethoxy group; an alkoxycarbonyl group having 1 to 30 carbon atoms such as a methoxycarbonyl group or an ethoxycarbonyl group; a phenoxy group; Aryloxy group; arylalkyloxy group such as benzyloxy group; α such as trifluoromethyl group Haloalkyl group, a hydroxyl group, aromatic such as thienyl group or a pyridyl group the heterocyclic group; an aromatic hydrocarbon ring group such as a phenyl group or a naphthyl group.

The oxidation potential of the benzodipyrrole compound can be adjusted by R ¹ and R ² . An electron donating group may be selected to lower the oxidation potential, and an electron accepting group may be selected to increase the oxidation potential. Further, by selecting those in the corresponding solvent as R ¹ and R ² is compatible, it can improve the solubility of benzodioxanyl pyrrole compounds.

  The monovalent organic groups exemplified above may have a further substituent. Further substituents include: hydroxyl group; halogen atom such as fluorine atom or chlorine atom; alkyl group having 1 to 6 carbon atoms such as methyl group or ethyl group; alkenyl group such as vinyl group; methoxycarbonyl group or ethoxycarbonyl group An alkoxycarbonyl group having 1 to 6 carbon atoms; an alkoxy group having 1 to 6 carbon atoms such as a methoxy group or an ethoxy group; an aryloxy group such as a phenoxy group; an arylalkyloxy group such as a benzyloxy group; a dimethylamino group, a diethylamino group Dialkylamino groups such as diisopropylamino group, dibenzylamino group or diphenethylamino group; diarylamino groups such as diphenylamino group or carbazolyl group; acyl groups such as acetyl group; haloalkyl groups such as trifluoromethyl group; Group; nitro group; Chirenjiokishi group or alkylenedioxy group having 1 to 3 carbon atoms ethylenedioxy and the like; and the like.

Among these, R ¹ and R ² are each independently a hydrogen atom, an optionally substituted aliphatic hydrocarbon group having 1 to 30 carbon atoms, or an optionally substituted carbon atom having 1 to 1 carbon atoms. It is preferable that it is an aromatic group which may have 30 alkoxy groups or a substituent. Examples of the substituent that these groups may have include those described above as further substituents that the monovalent organic group has.

  The C1-C30 aliphatic hydrocarbon group may be a saturated aliphatic hydrocarbon group or an unsaturated aliphatic hydrocarbon group. Further, it may be a linear hydrocarbon group or a branched hydrocarbon group. Examples of the aliphatic hydrocarbon group having 1 to 30 carbon atoms include an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an alkynyl group having 2 to 30 carbon atoms, and an alkadienyl group having 4 to 30 carbon atoms. Etc.

  The alkyl group having 1 to 30 carbon atoms is preferably an alkyl group having 1 to 10 carbon atoms, and more preferably an alkyl group having 1 to 6 carbon atoms. Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, or dodecanyl. Etc.

  The alkenyl group having 2 to 30 carbon atoms is preferably an alkenyl group having 2 to 10 carbon atoms, and more preferably an alkenyl group having 2 to 6 carbon atoms. Examples of alkenyl groups include, but are not limited to, vinyl, allyl, propenyl, isopropenyl, 2-methyl-1-propenyl, 2-methylallyl, or 2-butenyl. it can.

  The alkynyl group having 2 to 30 carbon atoms is preferably an alkynyl group having 2 to 10 carbon atoms, and more preferably an alkynyl group having 2 to 6 carbon atoms. Examples of the alkynyl group include, but are not limited to, an ethynyl group, a propynyl group, or a butynyl group.

  The alkadienyl group having 4 to 30 carbon atoms is preferably an alkadienyl group having 4 to 10 carbon atoms, and more preferably an alkadienyl group having 4 to 6 carbon atoms. Examples of alkadienyl groups include, but are not limited to, 1,3-butadienyl groups.

  The alkoxy group having 1 to 30 carbon atoms is preferably an alkoxy group having 1 to 10 carbon atoms, and more preferably an alkoxy group having 1 to 6 carbon atoms. Examples of the alkoxy group include, but are not limited to, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, or a pentyloxy group.

  Examples of the aromatic group include an aromatic hydrocarbon group and an aromatic heterocyclic group.

  As an aromatic hydrocarbon group, a C6-C30 thing is preferable and a C6-C20 thing is more preferable. Examples of the aromatic hydrocarbon group include a monocyclic aromatic hydrocarbon group such as a phenyl group; a ring-linked aromatic hydrocarbon group such as a 2-biphenylyl group, a 3-biphenylyl group, or a 4-biphenylyl group; a naphthyl group. (1-naphthyl group or 2-naphthyl group), an anthryl group (such as a 2-anthryl group or a 9-anthryl group), or an aromatic condensed ring group such as a fluorenyl group;

  Examples of the aromatic heterocyclic group include a monocyclic aromatic heterocyclic group, a ring-linked aromatic heterocyclic group, and a condensed aromatic heterocyclic group.

  As a monocyclic aromatic heterocyclic group, a C2-C30 thing is preferable and a C2-C20 thing is more preferable. Preferred examples of the monocyclic aromatic heterocyclic group include 5 to 14 membered rings, more preferably 5 to 10 membered rings, more preferably 1 to 4 heteroatoms as atoms constituting the ring, in addition to carbon atoms. Includes a 5- or 6-membered monocyclic aromatic heterocyclic group. Examples of the hetero atom include a nitrogen atom, a sulfur atom and an oxygen atom, and the monocyclic aromatic heterocyclic group preferably contains one or two hetero atoms as atoms constituting the ring.

  Specific examples of the monocyclic aromatic heterocyclic group include thienyl group (2-thienyl group or 3-thienyl group), furyl group (2-furyl group or 3-furyl group), pyridyl group (2-pyridyl group). , 3-pyridyl group, or 4-pyridyl group), thiazolyl group (2-thiazolyl group, 4-thiazolyl group, or 5-thiazolyl group), oxazolyl group (2-oxazolyl group, 4-oxazolyl group, or 5-oxazolyl group) Group), pyrazinyl group, pyrimidinyl group (2-pyrimidinyl group, 4-pyrimidinyl group or 5-pyrimidinyl group), pyrrolyl group (1-pyrrolyl group, 2-pyrrolyl group or 3-pyrrolyl group), imidazolyl group (1 -Imidazolyl group, 2-imidazolyl group, 4-imidazolyl group, or 5-imidazolyl group), pyrazolyl group (1- Lazolyl group, 3-pyrazolyl group or 4-pyrazolyl group), pyridazinyl group (3-pyridazinyl group or 4-pyridazinyl group), isothiazolyl group (3-isothiazolyl group etc.), isoxazolyl group (3-isoxazolyl group etc.), imidazolyl Group, and the like.

  As a condensed aromatic heterocyclic group, a C4-C30 thing is preferable and a C4-C20 thing is more preferable. Preferable examples of the fused aromatic heterocyclic group include an 8- to 20-membered ring, more preferably a 9- to 14-membered 2-ring having 1 to 4 heteroatoms as atoms constituting the ring in addition to the carbon atom. Or a tricyclic aromatic heterocyclic group is mentioned. Another preferred example of the fused aromatic heterocyclic group is from a 5- to 14-membered (preferably 5 to 10-membered) 7 to 10-membered aromatic heterocyclic bridge containing 1 to 4 hetero atoms in addition to the carbon atom. A monovalent group formed by removing any one hydrogen atom is used. Examples of the hetero atom include a nitrogen atom, a sulfur atom and an oxygen atom. The condensed aromatic heterocyclic group preferably contains one or two hetero atoms as atoms constituting the ring.

  Specific examples of the condensed aromatic heterocyclic group include a quinolyl group (such as a 2-quinolyl group, a 3-quinolyl group, a 4-quinolyl group, a 5-quinolyl group, or an 8-quinolyl group), an isoquinolyl group (1- Isoquinolyl group, 3-isoquinolyl group, 4-isoquinolyl group, or 5-isoquinolyl group), indolyl group (1-indolyl group, 2-indolyl group, 3-indolyl group, etc.), 2-benzothiazolyl group, benzo [b ] Thienyl group (such as 2-benzo [b] thienyl group or 3-benzo [b] thienyl group), benzo [b] furanyl group (such as 2-benzo [b] furanyl group or 3-benzo [b] furanyl group) Etc.

  As a ring connection aromatic heterocyclic group, a C4-C30 thing is preferable and a C4-C20 thing is more preferable. Examples of the ring-linked aromatic heterocyclic group include those in which at least one of the above-described monocyclic aromatic heterocyclic group, condensed aromatic heterocyclic group, and aromatic hydrocarbon group is bonded to each other.

More preferable examples of R ¹ and R ² include an optionally substituted aromatic group having 2 to 20 carbon atoms, or an optionally substituted alkyl group having 1 to 20 carbon atoms. Can be mentioned.

The aromatic group having 2 to 20 carbon atoms which may have a substituent is more preferably an aromatic hydrocarbon group having 6 to 20 carbon atoms which may have a halogen atom as a substituent. It is preferable that R ¹ and R ² are aromatic groups in that the interaction of the benzodipyrrole compound with the active layer can be improved.

The alkyl group having 1 to 20 carbon atoms which may have a substituent is more preferably an alkyl group having 2 to 12 carbon atoms which may have a substituent. R ¹ and R ² are preferably alkyl groups in that the carrier transport performance can be improved. The alkyl group having 1 to 20 carbon atoms which may have a substituent is more preferably an alkyl group having 2 to 12 carbon atoms having a substituent at the terminal, more preferably a carbon having a substituent at the terminal. It is a linear alkyl group of 2 to 12. The terminal substituent is preferably an ionic substituent such as an acidic substituent or a salt thereof, or a quaternary ammonium group. Specific examples of the acidic substituent include sulfonic acid groups (sulfo groups) and sulfines. A sulfur acid group containing an acid group (sulfino group); a phosphoric acid group (in a narrow sense), a phosphoric acid ester group, a phosphorous acid group, and a phosphoric acid group containing a phosphorous acid ester group; a carboxyl group; The salt of the acidic substituent refers to a substituent obtained by substituting the hydrogen ion of the acidic substituent with another cation. Specifically, the hydrogen atom of the acidic substituent is sodium or potassium. And those substituted with an alkaline earth metal such as calcium or magnesium. The quaternary ammonium group is preferably an ammonium group having three alkyl groups having 1 to 6 carbon atoms. It is preferable that R ¹ and R ² are alkyl groups from the viewpoint of improving carrier transport performance, and it is preferable that R ¹ and R ² have an ionic substituent from the viewpoint of further improving carrier transport efficiency. .

In the formula (I), R ³ and R ⁴ each independently represents a monovalent organic group. Examples of the monovalent organic group are each independently a hydrogen atom; an optionally substituted aliphatic hydrocarbon group having 1 to 30 carbon atoms; an optionally substituted carbon number 1 -30 alkoxy groups; aromatic groups optionally having substituents; acyl groups optionally having substituents; and the like. Examples of the optionally substituted aliphatic hydrocarbon group having 1 to 30 carbon atoms include alkyl groups having 1 to 6 carbon atoms such as a methyl group and an ethyl group; carbon having a sulfonic acid or a sulfonate group at the terminal An alkyl group having 1 to 6 carbon atoms; an alkyl group having 1 to 6 carbon atoms having a phosphate group at the terminal; an alkyl group having 1 to 6 carbon atoms having an alkyl ammonium salt at the terminal; an aralkyl group such as a benzyl group; a vinyl group and the like And the like. As the aromatic group which may have a substituent, an aromatic hydrocarbon ring group such as a phenyl group and a naphthyl group which may have a substituent; a thienyl group which may have a substituent, And aromatic heterocyclic groups such as pyridyl groups. Examples of the substituent include a halogen atom such as a fluorine atom; an alkyl group having 1 to 6 carbon atoms such as a methyl group and an ethyl group; an alkenyl group such as a vinyl group; an alkoxy having 1 to 6 carbon atoms such as a methoxy group and an ethoxy group. Groups; aryloxy groups such as phenoxy group and benzyloxy group; dialkylamino groups such as dimethylamino group and diethylamino group; diarylamino groups such as diphenylamino group; acyl groups such as carbazolyl group and acetyl group; trifluoromethyl group and the like Haloalkyl group and cyano group.

R ³ and R ⁴ are preferably an organic group having 0 to 25 carbon atoms, and more preferably an organic group having 0 to 20 carbon atoms in that the interaction between molecules tends to be improved.

When R ³ and R ⁴ are substituents having a π-conjugated electron such as an aromatic group, or substituents capable of controlling packing between molecules such as an alkyl group, it is possible to increase the amorphousness of the thin film. The ability to form a thin film can be improved.

Therefore, as a more preferable example of R ³ and R ⁴ , a hydrogen atom, an aromatic group having 2 to 20 carbon atoms which may have a substituent, or 1 to 1 carbon atom which may have a substituent. There are 20 alkyl groups.

In the formula (I), Ar ^{1 to} Ar ⁴ each independently represents an aromatic group which may have a substituent.

Specific examples of Ar ^{1 to} Ar ⁴ include those exemplified as the aromatic group which may have a substituent for R ¹ and R ² . Ar ^{1 to} Ar ⁴ are each independently preferably an aromatic group having 5 to 20 carbon atoms which may have a substituent, and 6 to carbon atoms optionally having a halogen atom as a substituent. More preferably, it is 20 aromatic hydrocarbon groups.

By selecting Ar ^{1 to} Ar ⁴ , in addition to increasing the amorphousness of the film, it is expected to improve the heat resistance of the film by controlling the glass transition temperature. In order to increase the amorphous property, a substituent having a pi-conjugated electron, specifically, an aromatic group such as a benzene ring group, a biphenyl group, or a naphthyl group is preferable. In order to increase the glass transition temperature, phenanthryl is preferable. Group, carbazolyl group and the like are preferable.

As a more preferable example of the benzodipyrrole compound, X ¹ is a nitrogen atom having a substituent R ² , X ² is a carbon atom having a substituent Ar ³ , and R ^{1 to} R ² and Ar ^{1 to} Ar ⁴ Are each independently an aromatic group having 5 to 20 carbon atoms which may have a substituent, and R ^{3 to} R ⁴ are a hydrogen atom, a methyl group, or a benzene ring group. In particular, R ^{1 to} R ² and Ar ^{1 to} Ar ⁴ are preferably an aromatic hydrocarbon group having 6 to 20 carbon atoms which may have a halogen atom as a substituent. Such a benzodipyrrole compound is preferable in that the interaction of the benzodipyrrole compound with the active layer can be improved.

As another preferred example of the benzodipyrrole compound, X ¹ is a carbon atom having a substituent Ar ³ , X ² is a nitrogen atom having a substituent R ² , and Ar ^{1 to} Ar ⁴ are each independently substituted An aromatic group having 5 to 20 carbon atoms which may have a group, R ^{1 to} R ² are each independently an alkyl group having 1 to 20 carbon atoms which may have a substituent, and R ³ to R ⁴ is a hydrogen atom include those a methyl group or a benzene ring group. In particular, it is preferable that R ^{1 to} R ² are each independently a C 2-12 alkyl group which may have a substituent. Such a benzodipyrrole compound is preferable in that the carrier transport performance can be improved.

  Specific examples (compounds P1 to P25) preferable as the benzodipyrrole compound of the present invention are listed below, but the benzodipyrrole compound of the present invention is not limited thereto. Further, although molecular structures having good symmetry are mainly exemplified, asymmetric benzodipyrrole compounds obtained by combining the structures of the compounds P1 to P25 can also be used.

  The photoelectric conversion element including the anode buffer layer 103 containing the benzodipyrrole compound of the present invention exhibits good photoelectric conversion efficiency. The reason is considered that the benzodipyrrole compound of the present invention has good hole mobility and electrical conductivity. In addition, the anode buffer layer 103 containing the benzodipyrrole compound of the present invention is considered to have a relatively small hole injection barrier with the electrode 102. In addition, since the buffer layer containing the benzodipyrrole compound of the present invention has an advantage that it can be easily formed uniformly, the film thickness can be further reduced.

(Method for producing benzodipyrrole compound of the present invention)
Although the synthesis method of the benzodipyrrole compound of this invention is not specifically limited, For example, it can synthesize | combine according to the following Reaction Formula. The following starting compounds can be synthesized according to known methods. For example, D.D. A. Kinsley, S.M. G. P. Plants. J. et al. Chem. Soc. , 1958, 1-7. Alternatively, the starting compound of the following formula can be synthesized by a coupling reaction between a corresponding diaminobenzene derivative and an alkynyl compound.

From the viewpoint of ease of synthesis operation, R ¹ = R ² is preferable, Ar ¹ = Ar ⁴ is also preferable, and Ar ² = Ar ³ is also preferable.

(Dopant)
The anode buffer layer 103 may further contain a dopant in addition to the benzodipyrrole compound of the present invention. By adding a dopant to the anode buffer layer 103, the conductivity of the anode buffer layer 103 can be controlled.

  In particular, it is preferable to add an electron-accepting compound (acceptor) as a dopant for improving photoelectric conversion efficiency. The reason for this is considered to be that when a benzodipyrrole compound is mixed with an electron accepting compound, a part of the benzodipyrrole compound is oxidized to generate a cation radical, and this cation radical functions as a hole carrier. .

Examples of the dopant include a metal oxide, an inorganic oxidizing agent, an organic oxidizing agent, or an acid. Examples of the metal oxide include molybdenum trioxide (MoO ₃ ), vanadium pentoxide (V ₂ O ₅ ), tungsten trioxide (WO ₃ ), and diantimony trioxide (Sb ₂ O ₃ ). Examples of the inorganic oxidizing agent include iodine. Examples of the organic oxidizing agent include quinodimethane compounds (for example, TCNQ, TCNP, TCQQ, F4-TCNQ), quinone derivatives (for example, DDQ), diaryliodonium salts (for example, TPFB), and organic metal compounds (for example, [FeCp ₂ ] PF ₆ Organic compounds containing trivalent iron). Examples of the acid include a strong Bronsted acid such as a sulfonic acid (eg, PSS, TsOH, or CSA) or antimonic acid (eg, TBPAH), or a strong Lewis acid such as a boron compound (eg, PPB).

Examples of the quinodimethane compound include the following compounds. In the following formula, R ⁵ represents a cyclic structure conjugated with a dicyanomethylene group, and a represents an integer of 2 or more and 4 or less.

  As a strong Bronsted acid, a pKa (in dimethyl sulfoxide) is preferably 10 or less, more preferably 5 or less, more preferably 3 or less, and particularly preferably 2 or less.

  In order to improve the photoelectric conversion efficiency, the difference between the value of the first ionization potential in the solid state of benzodipyrrole, which is an electron donating compound, and the electron affinity in the solid state of the dopant is −0.5 eV or more. It is also preferable that it is +0.5 eV or less. Moreover, it is also preferable that the electron affinity of the dopant in the solid state is 4 eV or more and 7 eV or less.

  The ionization potential of the benzodipyrrole compound in the solid state can be directly determined by, for example, photoelectron spectroscopy. The ionization potential may be determined electrochemically in solution. For this purpose, a cyclic voltammogram measurement method is used. The oxidation potential determined from the solution state can be converted to a solid state ionization potential using ferrocene as a standard substance. For example, the ionization potential of an example of the benzodipyrrole compound of the present invention is in the range of 4.5 to 5.5 eV.

  The electron affinity of the dopant can be determined by a cyclic voltammogram measurement method in a solution state, similarly to the ionization potential. In the solid state, it can be measured using inverse photoelectron spectroscopy. The electron affinity of the metal oxide is determined by inverse photoelectron spectroscopy, and values of 6.7 eV for molybdenum trioxide and 6.7 eV for vanadium pentoxide have been reported.

  The dopant may be contained in the whole anode buffer layer 103 or may be contained only in a part. For example, when the anode buffer layer 103 is composed of two or more layers, the dopant may be included in only a part of the layers.

  The amount of the dopant with respect to the whole anode buffer layer 103 is preferably 1% by weight or more, and preferably 50% by weight or less. When the amount of the dopant is within this range, the characteristics of the benzodipyrrole compound can be changed while maintaining the carrier transport efficiency by the benzodipyrrole compound.

  Among the benzodipyrrole compounds of the present invention, it is preferable to use those having higher chemical stability and thermal stability for the long-term stability of the photoelectric conversion element. Further, when the anode buffer layer 103 is positioned on the light receiving surface side of the photoelectric conversion element with respect to the active layer 104, the anode buffer layer 103 containing the benzodipyrrole compound of the present invention preferably has a light-transmitting property. The transmittance of visible light (light having a wavelength of 360 to 830 nm) is preferably 60% or more, and more preferably 80% or more.

  Examples of the method for forming the anode buffer layer 103 include a wet coating method such as a spin coating method and an ink jet method, and a vacuum deposition method. When the anode buffer layer 103 is formed by a coating method, a coating solution containing the benzodipyrrole compound of the present invention is prepared, this coating solution is applied, and the coating film is dried as necessary. This coating solution may further contain a dopant as necessary. When forming the anode buffer layer 103 by a vacuum evaporation method, the anode buffer layer 103 may be formed by a binary co-evaporation method.

  The thickness of the anode buffer layer 103 is not particularly limited, but is preferably 3 nm or more, and more preferably 10 nm or more from the viewpoint of obtaining a uniform film. On the other hand, from the viewpoint of reducing the internal resistance, it is preferably 200 nm or less, and more preferably 100 nm or less.

[1.3.2 Cathode buffer layer (105)]
The cathode buffer layer 105 is preferably capable of efficiently transporting electrons generated in the active layer 104 to the cathode 106. From this point of view, the cathode buffer layer 105 material preferably has a larger optical gap than the active layer 104 material in order to prevent exciton diffusion. The material of the cathode buffer layer 105 preferably has high electron transport properties and effectively lowers the work function of the cathode. The cathode buffer layer 105 is preferably in close physical contact with the adjacent active layer 104 and cathode 106.

  From these viewpoints, the material of the cathode buffer layer 105 includes an inorganic compound such as lithium fluoride (for example, described in Non-Patent Document 1) or a phenanthroline compound such as bathocuproine (BCP) (for example, S. Uchida et al. Appl. Phys. Lett. 84, 4218-4220, 2004.) and the like can be used.

  Examples of the method for forming the cathode buffer layer 105 include a wet coating method such as a spin coating method and an ink jet method, and a vacuum deposition method. The thickness of the cathode buffer layer 105 is not particularly limited, but is preferably 1 nm or more and more preferably 2 nm or more from the viewpoint of completely covering the active layer 104. On the other hand, from the viewpoint of reducing internal resistance and preventing a decrease in fill factor (FF), the thickness is preferably 100 nm or less, and more preferably 50 nm or less.

  When the cathode buffer layer 105 is positioned on the light receiving surface side of the photoelectric conversion element with respect to the active layer 104, the cathode buffer layer 105 preferably has a light-transmitting property, specifically visible light (wavelength 360 to 830 nm). Of light) is preferably 60% or more, and more preferably 80% or more.

<1.4 Active layer (104)>
The active layer 104 is not particularly limited as long as it is a layer containing an electron donor and an electron acceptor. The material used for the active layer 104 is a material that can efficiently absorb light whose wavelength is in the visible region to the near infrared region, and has high mobility to efficiently transport light-induced holes or electrons. It is preferable that

  Examples of the structure of the active layer include a heterojunction type and a bulk heterojunction type. The photoelectric conversion element according to the second embodiment shown in FIG. 2 is a heterojunction photoelectric conversion element. The active layer 104 of the heterojunction photoelectric conversion element has a two-layer structure including an active layer (p-layer) 104a containing an electron donor and an active layer (n-layer) 104b containing an electron acceptor. Have. Then, charge separation is performed at the junction interface between the active layer (p− layer) 104a and the active layer (n− layer) 104b.

  On the other hand, the photoelectric conversion element according to the first embodiment shown in FIG. 1 is a bulk heterojunction photoelectric conversion element. The active layer 104 of the bulk heterojunction photoelectric conversion element includes an active layer (i-layer) 104c in which an electron donor and an electron acceptor are mixed. From the viewpoint that the electron donor and the electron acceptor form a phase separation structure to increase the contact area between the two and charge separation is performed more efficiently, in the active layer (i-layer) 104c, It is preferable that the electron donor and the electron acceptor are phase-separated so as to have a size about the diffusion length of exciton.

  The bulk heterojunction active layer 104 may further include at least one of an active layer (p-layer) 104a and an active layer (n-layer) 104b. For example, the photoelectric conversion element according to the third embodiment shown in FIG. 3 includes an active layer 104 having a pin junction structure. An active layer 104 having a pin junction structure includes an active layer (p-layer) 104a containing an electron donor, an active layer (i-layer) 104c containing an electron donor and an electron acceptor, It has a three-layer structure in which an active layer (n-layer) 104b containing an electron acceptor is stacked.

Hereinafter, an electron donor and an electron acceptor used as a material for the active layer 104 will be described.
[1.4.1 Electron donor]
The electron donor used in the active layer is not particularly limited as long as it is a compound that functions as an electron donor. As an electron donor, a porphyrin compound and a phthalocyanine compound are mentioned, for example. These compounds may have a central metal or may not have a metal.

  Examples of the porphyrin compound include 21H, 23H-porphine, 21H, 23H-porphine metal complex, and the like. The porphyrin compound may have a substituent, and examples of the substituent that may be included include an aliphatic hydrocarbon group having 1 to 20 carbon atoms, an aromatic group having 2 to 20 carbon atoms, or a halogen atom. Can be mentioned. The substituents that the porphyrin compound has may be bonded to each other.

Among the porphyrin compounds, a benzoporphyrin compound represented by the following general formula (B1) or (B2) is preferable.

In formulas (B1) and (B2), Z ^1a , Z ^1b , Z ^2a , Z ^2b , Z ^3a , Z ^3b , Z ^4a and Z ^4b are each independently a monovalent organic group, and Z ^1a and Z ^1b , Z ^2a and Z ^2b , Z ^3a and Z ^3b , and Z ^4a and Z ^4b may combine to form a ring.

For Z ^1a , Z ^1b , Z ^2a , Z ^2b , Z ^3a , Z ^3b , Z ^4a and Z ^4b , examples of the monovalent organic group include a hydrogen atom, a halogen atom, a hydroxyl group and a substituent. May be an aliphatic hydrocarbon group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms which may have a substituent, and an aryloxy group having 2 to 30 carbon atoms which may have a substituent. , An amino group which may have a substituent, a silyl group which may have a substituent, an alkylthio group which may have a substituent (-SR ²¹ , wherein R ²¹ represents a substituent. Represents an optionally substituted alkyl group having 1 to 30 carbon atoms), an optionally substituted arylthio group (—SR ²² , wherein R ²² is a carbon that may have a substituent). Represents an aryl group of 2 to 18), and may have a substituent Alkylsulfonyl group _(-SO ^{2 R 23, wherein, R 23} represents an alkyl group having 1 to 30 carbon atoms which may have a substituent), optionally substituted aryl sulfonyl group ( -SO 2 _R ^24, wherein, R ²⁴ represents an aryl group having 2 to 18 carbon atoms which may have a substituent), a cyano group, an acyl group, an alkoxycarbonyl may have a substituent A group, a dialkylamino group which may have a substituent, a diaralkylamino group which may have a substituent, an α-haloalkyl group which may have a substituent, or a substituent. An aromatic group which may be used. Among these, Z ^1a , Z ^1b , Z ^2a , Z ^2b , Z ^3a , Z ^3b , Z ^4a and Z ^4b are each independently a single atom such as a hydrogen atom or a halogen atom, or an aromatic group. Is preferred. In addition, the set of Z ^1a and Z ^1b , the set of Z ^2a and Z ^2b , the set of Z ^3a and Z ^3b, and the set of Z ^4a and Z ^4b may each represent the same set of substituents. Also preferred.

In formulas (B1) and (B2), examples of the ring formed by combining Z ^ia and Z ^ib (i = 1 to 4) include, for example, an optionally substituted benzene ring and naphthalene ring. Or an aromatic hydrocarbon ring such as an anthracene ring; an aromatic heterocyclic ring such as a pyridine ring, a quinoline ring, a furan ring, or a thiophene ring which may have a substituent; a non-aromatic cyclic hydrocarbon such as a cyclohexane ring Ring; and the like.

In formulas (B1) and (B2), R ^{9 to} R ¹² are each independently a monovalent organic group.

Examples of the monovalent organic group for R ^{9 to} R ¹² include a hydrogen atom, a halogen atom, a hydroxyl group, an optionally substituted aliphatic hydrocarbon group having 1 to 30 carbon atoms, and a substituent. An optionally substituted alkoxy group having 1 to 30 carbon atoms, an aryloxy group having 2 to 30 carbon atoms that may have a substituent, an amino group optionally having a substituent, and a substituent. An optionally substituted silyl group, an optionally substituted alkylthio group (-SR ²¹ , wherein R ²¹ represents an optionally substituted alkyl group having 1 to 30 carbon atoms), An arylthio group which may have a substituent (-SR ²² , wherein R ²² represents an aryl group having 2 to 18 carbon atoms which may have a substituent); which may alkylsulfonyl group _(-SO ^{2 R 23, wherein, R 23} is a substituted group It has also represent an alkyl group having 1 to 30 carbon atoms), which may have a substituent arylsulfonyl group (-SO 2 _R ^24, wherein, R ²⁴ is substituted A cyano group, an acyl group, an optionally substituted alkoxycarbonyl group, an optionally substituted dialkylamino group, and a substituted group. A diaralkylamino group which may be substituted, an α-haloalkyl group which may have a substituent, or an aromatic group which may have a substituent.

Among these, R ^{9 to} R ¹² are preferably selected from a single atom such as a hydrogen atom or a halogen atom in order to improve the planarity of the compound molecule.

In the formula (B2), M is an atomic group in which a divalent metal atom or a trivalent or higher metal and another atom are bonded. Examples of the divalent metal atom include Zn, Cu, Fe, Ni, Co, and the like, and examples of the atomic group in which a trivalent or higher valent metal and another atom are bonded include, for example, Fe—R ²⁵ , Al—. ^{R 26, Ti = O, Si} -R 27 R 28, and the like. Here, R ^{25 to} R ²⁸ each independently represents a monovalent organic group, and preferred examples of R ^{25 to} R ²⁸ include a halogen atom, an alkyl group, or an alkoxy group.

  Preferred examples of the benzoporphyrin compound used for the electron donor include compounds represented by the following formulas BP-1 to BP-10, or 2,3,7,8,12,13,17,18-21H, Examples thereof include 23H-tetrabenzoporphine platinum. However, the benzoporphyrin compound used as the electron donor is not limited to the following compounds. In the following, compounds having a highly symmetrical molecular structure are exemplified, but compounds having an asymmetric structure obtained by combining the respective partial structures can also be used as the electron donor.

  Examples of the phthalocyanine compound used as the electron donor include phthalocyanine or a phthalocyanine metal complex. More specific examples of the phthalocyanine compound include 29H, 31H-phthalocyanine, copper phthalocyanine, zinc phthalocyanine, tin phthalocyanine, titanium phthalocyanine oxide, lead phthalocyanine, indium phthalocyanine chloride, aluminum chloride phthalocyanine, copper 4, 4 ′, 4 ″. , 4 ′ ″-tetraaza-29H, 31H-phthalocyanine and the like.

  Another example of the electron donor is a conjugated polymer compound. Specific examples of the conjugated polymer compound include those having polythiophene, polyparaphenylene vinylene, or polyfluorene as a basic skeleton. Specific examples are shown below. However, the conjugated polymer compound used as the electron donor is not limited to the following compounds. In the following formula, parentheses indicate a repeating unit. Such a layer containing a conjugated polymer compound can be formed by a wet coating method or the like.

  The electron donor included in the active layer 104 may be a mixture of two or more electron donors.

[1.4.2 Electron acceptor]
The electron acceptor contained in the active layer 104 is not particularly limited as long as it is a compound that functions as an electron donor. It is preferable that the electron acceptor used for the active layer 104 can efficiently receive electrons from the electron donor and efficiently transport the electrons to the electrode 106 through the buffer layer 105.

In order to efficiently receive electrons, the LUMO energy level of the electron donor is preferably 0.3 eV or more higher than the LUMO energy level of the electron acceptor, and the electron affinity of the electron acceptor is higher than that of the electron donor. It is preferably higher by 0.3 eV or more. In order to transport electrons efficiently, the electron mobility of the electron acceptor is preferably 10 ⁻⁴ cm ² / V · s or more.

The electron acceptor is preferably fullerene or a fullerene derivative. Here, the fullerene is a carbon cluster having a closed shell structure, and the carbon number of the fullerene is not particularly limited as long as it is usually an even number of 60 or more and 130 or less. Examples of fullerenes include C ₆₀ , C ₇₀ , C ₇₆ , C ₇₈ , C ₈₂ , C ₈₄ , C ₉₀ , C ₉₄ , C ₉₆ and higher carbon clusters having more carbon than these. . Among these, _C60 or _C70 is preferable. As fullerenes, carbon-carbon bonds on some fullerene rings may be broken. Some carbon atoms may be replaced with other atoms. Furthermore, a metal atom, a nonmetal atom, or an atomic group composed of these may be included in the fullerene cage.

  The fullerene derivative is a fullerene having a substituent, and examples of the substituent include an alkyl group having 1 to 20 carbon atoms which may have a substituent. Examples of the substituent that the alkyl group has include an aromatic group, an alkyloxycarbonyl group, or a silyl group.

  Examples of fullerenes and fullerene derivatives used as electron acceptors are shown below. However, fullerenes or fullerene derivatives used as electron acceptors are not limited to the following compounds.

  The electron acceptor included in the active layer 104 may be a mixture of two or more kinds of electron acceptors.

[1.4.3 Method for forming active layer]
The method for forming the active layer 104 is not particularly limited, and an active layer forming method suitable for the properties of the electron acceptor, the electron donor, and the like included in the active layer 104 is used. As a method for forming the active layer 104 (each layer constituting these when the active layer 104 is composed of a plurality of layers), for example, an electron acceptor, an electron donor or a mixture thereof constituting the active layer is prepared, Examples thereof include a method of forming a film by a vacuum deposition method or a wet coating method.

  When the active layer material has sublimability, a vacuum deposition method can be used. When the active layer material is soluble in an appropriate solvent, a coating method such as a spin coating method, a casting method, a blade coating method, an ink jet method, or a gravure printing method can be used. In order to control the crystallinity and shape of the thin film, it is preferable to form the active layer by a wet coating method.

  In particular, as a method of forming the active layer (i-layer) 104c containing an electron donor and an electron acceptor, a method of co-evaporating the electron donor and the electron acceptor by using a vacuum deposition method can be given. It is done. Moreover, the method of apply | coating the mixed solution containing an electron donor and an electron acceptor using the apply | coating method is also mentioned.

  When the active layer 104 of the photoelectric conversion element according to the second embodiment shown in FIG. 2 is formed, an active layer (p-layer) 104a containing an electron donor and an active layer containing an electron acceptor ( n-layer) 104b may be stacked. When the active layer 104 of the photoelectric conversion element according to the first embodiment shown in FIG. 1 is formed, an active layer (i-layer) 104c containing an electron donor and an electron acceptor may be formed. When forming the active layer 104 of the photoelectric conversion element according to the third embodiment shown in FIG. 3, an active layer (p-layer) 104a containing an electron donor, an electron donor and an electron acceptor And an active layer (n-layer) 104b containing an electron acceptor.

  The average film thickness of the active layer 104 formed in this way is preferably 10 nm or more, more preferably 20 nm or more, from the viewpoint of increasing the portion that absorbs light. On the other hand, from the viewpoint of promoting the transport of the generated carrier, it is preferably 2000 nm or less, more preferably 1000 nm or less.

  When a benzoporphyrin compound is used as an electron donor, it may not be easy to form a layer containing the benzoporphyrin compound using a wet coating method because the benzoporphyrin compound has a relatively low solubility in an organic solvent or the like. . In order to form a layer containing a benzoporphyrin compound, a layer containing a soluble benzoporphyrin compound precursor can be formed by a wet coating method, and then the benzoporphyrin compound precursor can be converted into a benzoporphyrin compound. .

  For example, the benzoporphyrin compound represented by the general formula (B1) or (B2) can be obtained by a thermal conversion reaction of a benzoporphyrin compound precursor represented by the following general formula (C1) or (C2).

In the formulas (C1) and (C2), Z ^1a , Z ^1b , Z ^2a , Z ^2b , Z ^3a , Z ^3b , Z ^4a , Z ^4b , R ^{9 to} R ¹² , and M are each represented by the formula (B1). And (B2).

In formulas (C1) and (C2), Y ^{1 to} Y ⁴ each independently represent a monovalent organic group. In formulas (C1) and (C2), ^four Y ^{1 to} Y 4 are present, but Y ¹ , Y ² , Y ^3, and Y ⁴ may be the same or different. Good.

With respect to Y ^{1 to} Y ⁴ , examples of the monovalent organic group include a hydrogen atom, a halogen atom, a hydroxyl group, an optionally substituted aliphatic hydrocarbon group having 1 to 30 carbon atoms, and a substituent. An optionally substituted alkoxy group having 1 to 30 carbon atoms, an aryloxy group having 2 to 30 carbon atoms that may have a substituent, an amino group optionally having a substituent, and a substituent. An optionally substituted silyl group, an optionally substituted alkylthio group (-SR ²¹ , wherein R ²¹ represents an optionally substituted alkyl group having 1 to 30 carbon atoms), An arylthio group which may have a substituent (-SR ²² , wherein R ²² represents an aryl group having 2 to 18 carbon atoms which may have a substituent); which may alkylsulfonyl group _(-SO ^{2 R 23, wherein, R 23} is a substituent And it represents an even better alkyl group having 1 to 30 carbon atoms optionally) substituent has optionally may be an arylsulfonyl group (-SO 2 _R ^24, wherein, R ²⁴ is optionally substituted A C2-C18 aryl group), a cyano group, an acyl group, an optionally substituted alkoxycarbonyl group, an optionally substituted dialkylamino group, and a substituent. Examples thereof include a diaralkylamino group which may be substituted, an α-haloalkyl group which may have a substituent, and an aromatic group which may have a substituent.

  A method for forming the active layer (p-layer) 104a containing the electron donor by the wet coating method will be described below by taking the benzoporphyrin compound BP-1 as an example. Bicyclo compound CP-1 which is a precursor of benzoporphyrin compound BP-1 does not have a planar structure, has relatively high solubility in a solvent and low crystallinity. For this reason, the favorable film | membrane close | similar to an amorphous state or an amorphous state can be obtained by apply | coating the solution of bicyclo compound CP-1. By heating this film, a film of a highly planar benzoporphyrin compound BP-1 can be obtained by reverse Diels-Alder reaction (deethylene reaction).

This conversion reaction is preferably performed at 100 ° C. or higher, more preferably 150 ° C. or higher, in order to sufficiently proceed. Y ^{1 to} Y ⁴ are particularly preferably each independently a hydrogen atom or a methyl group. In this case, the compound that is eliminated from the precursor is ethylene, propene, butene, or the like, and hardly remains in the active layer, and there are few problems in terms of toxicity and safety.

  In the case of forming an active layer (p-layer) 104a containing another benzoporphyrin compound, an active layer (p-layer) is similarly formed by applying a corresponding bicyclo precursor solution and performing a conversion reaction. 104a can be formed. Also, when forming an active layer (i-layer) 104c containing a benzoporphyrin compound and an electron acceptor, a conversion reaction is performed by applying a solution containing the corresponding bicyclo precursor and the electron acceptor. Thus, the active layer (i-layer) 104c can be similarly formed.

<2. Solar cell>
The photoelectric conversion element according to each of the above-described embodiments is preferably used as a solar cell, particularly a solar cell element of a thin film solar cell. FIG. 4 is a cross-sectional view schematically showing the configuration of a thin film solar cell as one embodiment of the present invention. As shown in FIG. 4, the thin film solar cell 14 of this embodiment includes a weather-resistant protective film 1, an ultraviolet cut film 2, a gas barrier film 3, a getter material film 4, a sealing material 5, and a solar cell element. 6, a sealing material 7, a getter material film 8, a gas barrier film 9, and a back sheet 10 are provided in this order. And light is irradiated from the side (downward in the figure) where the weather-resistant protective film 1 is formed, and the solar cell element 6 generates power. In addition, when using a highly waterproof sheet such as a sheet in which a fluororesin film is bonded to both surfaces of an aluminum foil as the back sheet 10 described later, the getter material film 8 and / or the gas barrier film 9 may not be used depending on the application. Good.

[2.1 Weatherproof protective film (1)]
The weather-resistant protective film 1 is a film that protects the solar cell element 6 from weather changes. By covering the solar cell element 6 with the weather-resistant protective film 1, the solar cell element 6 and the like are protected from weather changes and the power generation capacity is kept high. Since the weather resistant protective film 1 is located on the outermost layer of the thin film solar cell 14, the surface covering material of the thin film solar cell 14 such as weather resistance, heat resistance, transparency, water repellency, stain resistance and / or mechanical strength is provided. It is preferable to have a property suitable for the above and to maintain it for a long period of time in outdoor exposure.

  Moreover, the weather-resistant protective film 1 is preferably one that transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the light transmittance of visible light (wavelength 360 to 830 nm) is preferably 80% or more, and the upper limit is not limited.

  Furthermore, since the thin-film solar cell 14 is often heated by receiving light, it is preferable that the weather-resistant protective film 1 also has heat resistance. From this viewpoint, the melting point of the constituent material of the weather-resistant protective film 1 is usually 100 ° C. or higher and 350 ° C. or lower.

  The material which comprises the weather-resistant protective film 1 is arbitrary as long as it can protect the solar cell element 6 from a weather change. Examples of the material include polyethylene resin, polypropylene resin, cyclic polyolefin resin, AS (acrylonitrile-styrene) resin, ABS (acrylonitrile-butadiene-styrene) resin, polyvinyl chloride resin, fluorine resin, polyethylene terephthalate, polyethylene Examples thereof include polyester resins such as naphthalate, phenol resins, polyacrylic resins, polyamide resins such as various nylons, polyimide resins, polyamide-imide resins, polyurethane resins, cellulose resins, silicone resins, and polycarbonate resins.

  In addition, the weather-resistant protective film 1 may be formed with 1 type of material, and may be formed with 2 or more types of materials. Moreover, although the weather-resistant protective film 1 may be formed with the single layer film, the laminated | multilayer film provided with the film of two or more layers may be sufficient as it.

  The thickness of the weather-resistant protective film 1 is not particularly defined, but is usually 10 μm or more and 200 μm or less.

  Moreover, you may perform surface treatment, such as a corona treatment and / or a plasma treatment, for the weather-resistant protective film 1 in order to improve the adhesiveness with another film.

  The weatherproof protective film 1 is preferably provided on the outer side as much as possible in the thin-film solar cell 14. This is because more of the constituent members of the thin-film solar cell 14 can be protected.

[2.2 UV cut film (2)]
The ultraviolet cut film 2 is a film that prevents the transmission of ultraviolet rays. The ultraviolet cut film 2 is provided in the light receiving portion of the thin-film solar cell 14, and the ultraviolet cut film 2 covers the light receiving surface 6a of the solar cell element 6, so that the solar cell element 6 and, if necessary, the gas barrier films 3 and 9 are exposed to ultraviolet rays. The power generation capacity can be maintained at a high level.

  The degree of the ability to suppress the transmission of ultraviolet rays required for the ultraviolet cut film 2 is preferably such that the transmittance of ultraviolet rays (for example, wavelength of 300 nm) is 50% or less, and there is no limit on the lower limit. Further, the ultraviolet cut film 2 is preferably one that transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the light transmittance of visible light (wavelength 360 to 830 nm) is preferably 80% or more, and the upper limit is not limited.

  Furthermore, since the thin film solar cell 14 is often heated by receiving light, the ultraviolet cut film 2 preferably has heat resistance. From this viewpoint, the melting point of the constituent material of the ultraviolet cut film 2 is usually 100 ° C. or higher and 350 ° C. or lower.

  Moreover, the ultraviolet cut film 2 has a high softness | flexibility, its adhesiveness with an adjacent film is favorable, and what can cut water vapor | steam and oxygen is preferable.

  The material which comprises the ultraviolet cut film 2 is arbitrary if the intensity | strength of an ultraviolet-ray can be weakened. Examples of the material include films formed by blending an ultraviolet absorber with an epoxy, acrylic, urethane, or ester resin. Further, a film in which a layer of an ultraviolet absorbent dispersed or dissolved in a resin (hereinafter referred to as “ultraviolet absorbing layer” as appropriate) is formed on a base film may be used.

  As the ultraviolet absorber, for example, a salicylic acid-based, benzophenone-based, benzotriazole-based, or cyanoacrylate-based one can be used. In addition, a ultraviolet absorber may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  As described above, a film in which an ultraviolet absorbing layer is formed on a base film can also be used as the ultraviolet absorbing film. Such a film can be produced, for example, by applying a coating solution containing an ultraviolet absorber on a substrate film and drying it.

  Although the material of a base film is not specifically limited, For example, polyester is mentioned at the point from which the balance of heat resistance and a softness | flexibility is obtained.

  When an example of a specific product of the ultraviolet cut film 2 is given, cut ace (manufactured by MKV Plastic Co., Ltd.) and the like can be mentioned.

  In addition, the ultraviolet cut film 2 may be formed with 1 type of material, and may be formed with 2 or more types of materials. Further, the ultraviolet cut film 2 may be formed of a single layer film, but may be a laminated film including two or more layers. The thickness of the ultraviolet cut film 2 is not particularly limited, but is usually 5 μm or more and 200 μm or less.

  Although the ultraviolet cut film 2 should just be provided in the position which covers at least one part of the light-receiving surface 6a of the solar cell element 6, Preferably it is provided in the position which covers all the light-receiving surfaces 6a of the solar cell element 6. FIG. However, the ultraviolet cut film 2 may be provided at a position other than the position covering the light receiving surface 6 a of the solar cell element 6.

[2.3 Gas barrier film (3)]

  The gas barrier film 3 is a film that prevents permeation of water and oxygen. By covering the solar cell element 6 with the gas barrier film 3, the solar cell element 6 can be protected from water and oxygen, and the power generation capacity can be kept high.

The degree of moisture resistance required for the gas barrier film 3 varies depending on the type of the solar cell element 6 and the like. For example, when the solar cell element 6 is an organic solar cell element, the water vapor transmission rate per unit area (1 m ² ) is usually 1 × 10 ⁻¹ g / m ² / day or less. Is preferred, and there is no limit to the lower limit.

The degree of oxygen permeability required for the gas barrier film 3 varies depending on the type of the solar cell element 6 and the like. For example, when the solar cell element 6 is an organic solar cell element, the oxygen transmission rate per unit area (1 m ² ) is usually 1 × 10 ⁻¹ cc / m ² / day / atm or less. There is preferably no lower limit.

  Further, the gas barrier film 3 is preferably one that transmits visible light from the viewpoint of not preventing the light absorption of the solar cell element 6. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 60% or more, and there is no upper limit.

  Furthermore, since the thin film solar cell 14 is often heated by receiving light, it is preferable that the gas barrier film 3 also has heat resistance. From this viewpoint, the melting point of the constituent material of the gas barrier film 3 is usually 100 ° C. or higher and 350 ° C. or lower.

  The specific configuration of the gas barrier film 3 is arbitrary as long as the solar cell element 6 can be protected from water. However, since the manufacturing cost increases as the amount of water vapor or oxygen that can permeate the gas barrier film 3 increases, it is preferable to use an appropriate film considering these points comprehensively.

Particularly suitable gas barrier film 3 includes, for example, a film obtained by vacuum-depositing SiO _x on a base film such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN).

  In addition, the gas barrier film 3 may be formed with 1 type of material, and may be formed with 2 or more types of materials. The gas barrier film 3 may be formed of a single layer film, but may be a laminated film including two or more layers.

  The thickness of the gas barrier film 3 is not particularly defined, but is usually 5 μm or more and 200 μm or less.

  As long as the gas barrier film 3 can cover the solar cell element 6 and protect it from moisture and oxygen, the formation position is not limited, but the front surface of the solar cell element 6 (surface on the light receiving surface side, lower surface in FIG. 4) and It is preferable to cover the back surface (the surface opposite to the light receiving surface; the upper surface in FIG. 4). This is because the front and back surfaces of the thin film solar cell 14 are often formed in a larger area than the other surfaces. In this embodiment, the gas barrier film 3 covers the front surface of the solar cell element 6, and a gas barrier film 9 described later covers the back surface of the solar cell element 6. In addition, when using a highly waterproof sheet such as a sheet in which a fluororesin film is bonded to both surfaces of an aluminum foil as the back sheet 10 described later, the getter material film 8 and / or the gas barrier film 9 may not be used depending on the application. Good.

[2.4 Getter material film (4)]
The getter material film 4 is a film that absorbs moisture and / or oxygen. By covering the solar cell element 6 with the getter material film 4, the solar cell element 6 and the like are protected from moisture and / or oxygen, and the power generation capacity is kept high. Here, unlike the gas barrier film 3 as described above, the getter material film 4 does not prevent moisture permeation but absorbs moisture. By using a film that absorbs moisture, the getter material film 4 captures moisture that slightly enters the space formed by the gas barrier films 3 and 9 when the solar cell element 6 is covered with the gas barrier film 3 or the like. The influence of moisture on the solar cell element 6 can be eliminated.

The degree of moisture absorption capacity of the getter material film 4 is usually 0.1 mg / cm ² or more, and although there is no upper limit, it is usually 10 mg / cm ² or less.

  Further, when the solar cell element 6 is covered with the gas barrier films 3 and 9 or the like by the getter material film 4 absorbing oxygen, the oxygen that slightly enters the space formed by the gas barrier films 3 and 9 is obtained as the getter material. The film 4 can capture and eliminate the influence of oxygen on the solar cell element 6.

  Furthermore, the getter material film 4 is preferably one that transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 60% or more, and there is no upper limit.

  Furthermore, since the thin film solar cell 14 is often heated by receiving light, the getter material film 4 preferably has heat resistance. From this viewpoint, the melting point of the constituent material of the getter material film 4 is usually 100 ° C. or higher and 350 ° C. or lower.

  The material constituting the getter material film 4 is arbitrary as long as it can absorb moisture and / or oxygen. Examples of the material include alkali metal, alkaline earth metal or alkaline earth metal oxides; alkali metal or alkaline earth metal hydroxides; silica gel, zeolitic compounds, magnesium sulfate. And sulfates such as sodium sulfate and nickel sulfate; and organometallic compounds such as aluminum metal complexes and aluminum oxide octylates. Specifically, examples of the alkaline earth metal include Ca, Sr, and Ba. Examples of the alkaline earth metal oxide include CaO, SrO, and BaO. In addition, Zr-Al-BaO and aluminum metal complexes are also included. Specific product names include, for example, OleDry (Futaba Electronics).

  Examples of the substance that absorbs oxygen include activated carbon, silica gel, activated alumina, molecular sieve, magnesium oxide, and iron oxide. In addition, Fe, Mn, Zn, and inorganic salts such as sulfates, chlorides, and nitrates of these metals are also included.

  In addition, the getter material film 4 may be formed of one type of material or may be formed of two or more types of materials. The getter material film 4 may be formed of a single layer film, but may be a laminated film including two or more layers.

  The thickness of the getter material film 4 is not particularly specified, but is usually 5 μm or more and 200 μm or less.

  If the getter material film 4 is in the space formed by the gas barrier films 3 and 9, the formation position is not limited, but the front surface of the solar cell element 6 (light receiving surface side surface; lower surface in FIG. 4). And it is preferable to cover the back surface (surface opposite to the light receiving surface; upper surface in FIG. 4). This is because, in the thin film solar cell 14, the front and back surfaces are often formed in a larger area than the other surfaces, and therefore moisture and oxygen tend to enter through these surfaces. From this viewpoint, the getter material film 4 is preferably provided between the gas barrier film 3 and the solar cell element 6. In this embodiment, the getter material film 4 covers the front surface of the solar cell element 6, a getter material film 8 described later covers the back surface of the solar cell element 6, and the getter material films 4 and 8 are respectively the solar cell element 6 and the gas barrier film 3. , 9 are located between them. In addition, when using a highly waterproof sheet such as a sheet obtained by bonding a fluororesin film on both surfaces of an aluminum foil as the back sheet 10 described later, the getter material film 8 and / or the gas barrier film 9 may not be used depending on the application. .

[2.5 Sealant (5)]
The sealing material 5 is a film that reinforces the solar cell element 6. Since the solar cell element 6 is thin, the strength is usually weak, and thus the strength of the thin film solar cell tends to be weak. However, the strength can be maintained high by the sealing material 5.

  Moreover, it is preferable that the sealing material 5 has high strength from the viewpoint of maintaining the strength of the thin-film solar cell 14. The specific strength is related to the strength of the weatherproof protective film 1 other than the sealing material 5 and the strength of the back sheet 10 and is generally difficult to define, but the thin film solar cell 14 as a whole has good bending workability. However, it is desirable to have a strength that does not cause peeling of the bent portion.

  In addition, the sealing material 5 is preferably one that transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 60% or more, and there is no upper limit.

  The thickness of the sealing material 5 is not particularly specified, but is usually 2 μm or more and usually 700 μm or less.

  The T-type peel adhesion strength of the sealing material 5 to the substrate is usually 1 N / inch or more and usually 2000 N / inch or less. It is preferable that the T-type peel adhesive strength is 1 N / inch or more in terms of ensuring the long-term durability of the module. It is preferable that the T-type peel adhesive strength is 2000 N / inch or less in that the base material, the barrier film, and the adhesive can be separated and discarded when the solar cell module is discarded. The T-type peel adhesion strength is measured by a method according to JIS K6854.

  The constituent material of the sealing material 5 is not particularly limited as long as it has the above characteristics, but sealing of organic / inorganic solar cells, sealing of organic / inorganic LED elements, sealing of electronic circuit boards, etc. In general, a sealing material generally used can be used.

  Specifically, a thermosetting resin composition or a thermoplastic resin composition and an active energy ray curable resin composition can be mentioned. The active energy ray-curable resin composition is, for example, a resin that is cured by ultraviolet rays, visible light, electron beams, or the like. More specifically, an ethylene-vinyl acetate copolymer (EVA) resin composition, a hydrocarbon resin composition, an epoxy resin composition, a polyester resin composition, an acrylic resin composition, and a urethane resin composition. Or a silicone-based resin composition, etc., depending on the main chain, branched chain, terminal chemical modification of each polymer, adjustment of molecular weight, additives, etc., thermosetting, thermoplastic and active energy ray curable, etc. The characteristics are expressed.

  Moreover, since the thin film solar cell 14 is often heated by receiving light, it is preferable that the sealing material 5 also has heat resistance. From this viewpoint, the melting point of the constituent material of the sealing material 5 is usually 100 ° C. or higher and 350 ° C. or lower.

The density of the constituent material for sealing material in the sealing material 5 is preferably 0.80 g / cm ³ or more, and there is no upper limit. The measurement and evaluation of density can be performed by a method based on JIS K7112.

  Although there is no restriction | limiting in the position which provides the sealing material 5, Usually, it provides so that the solar cell element 6 may be inserted | pinched. This is for reliably protecting the solar cell element 6. In this embodiment, the sealing material 5 and the sealing material 7 are provided on the front surface and the back surface of the solar cell element 6, respectively.

[2.6 Solar cell element (6)]
The solar cell element 6 is the same as the photoelectric conversion element according to each embodiment described above. Although only one solar cell element 6 may be provided for each thin film solar cell 14, usually two or more solar cell elements 6 are provided. The specific number of solar cell elements 6 can be arbitrarily set. When a plurality of solar cell elements 6 are provided, the solar cell elements 6 are often arranged in an array.

  When a plurality of solar cell elements 6 are provided, the solar cell elements 6 are usually electrically connected to each other, and electricity generated from the connected group of solar cell elements 6 is taken out from a terminal (not shown). At this time, the solar cell elements are usually connected in series in order to increase the voltage. Thus, when connecting the solar cell elements 6, it is preferable that the distance between the solar cell elements 6 is small, and by extension, the gap between the solar cell element 6 and the solar cell element 6 is preferably narrow. This is because the light receiving area of the solar cell element 6 is widened to increase the amount of received light, and the amount of power generated by the thin film solar cell 14 is increased.

[2.7 Sealant (7)]
The sealing material 7 is a film similar to the sealing material 5 described above, and the same material as the sealing material 7 can be used in the same manner except that the arrangement position is different. Moreover, since the constituent member on the back side of the solar cell element 6 does not necessarily need to transmit visible light, a member that does not transmit visible light can be used.

[2.8 Getter material film (8)]
The getter material film 8 is the same film as the getter material film 4 described above, and the same material as the getter material film 4 can be used as necessary, except for the arrangement position. Moreover, since the constituent member on the back side of the solar cell element 6 does not necessarily need to transmit visible light, a member that does not transmit visible light can be used.

[2.9 Gas barrier film (9)]
The gas barrier film 9 is the same film as the gas barrier film 3 described above, and the same material as the gas barrier film 9 can be used as necessary except that the arrangement position is different. Moreover, since the constituent member on the back side of the solar cell element 6 does not necessarily need to transmit visible light, a member that does not transmit visible light can be used.

[2.10 Back sheet (10)]
The back sheet 10 is the same film as the weather-resistant protective film 1 described above, and the same material as the weather-resistant protective film 1 can be used in the same manner except that the arrangement position is different. In addition, if the back sheet 10 is difficult to permeate water and oxygen, the back sheet 10 can also function as a gas barrier layer. Moreover, since the constituent member on the back side of the solar cell element 6 does not necessarily need to transmit visible light, a member that does not transmit visible light can be used.

[2.11 Dimensions, etc.]
The thin film solar cell 14 of the present embodiment is usually a thin film member. Thus, by forming the thin film solar cell 14 as a film-like member, the thin film solar cell 14 can be easily installed in a building material, an automobile, an interior, or the like. The thin-film solar cell 14 is light and difficult to break, and thus a highly safe solar cell can be obtained and can be applied to a curved surface, so that it can be used for more applications. Since it is thin and light, it is preferable in terms of distribution such as transportation and storage. Furthermore, since it is in the form of a film, it can be manufactured in a roll-to-roll manner, and the cost can be greatly reduced. Although there is no restriction | limiting in the specific dimension of the thin film solar cell 14, The thickness is usually 300 micrometers or more and 3000 micrometers or less.

[2.12 Manufacturing method]
Although there is no restriction | limiting in the manufacturing method of the thin film solar cell 14 of this embodiment, For example, as a solar cell manufacturing method of the form of FIG. 4, after producing the laminated body shown by FIG. Is mentioned. Since the solar cell element of the present invention is excellent in heat resistance, it is preferable in that deterioration due to the laminate sealing step is reduced.

  The laminate production shown in FIG. 4 can be performed using a known technique. The method of the laminate sealing step is not particularly limited as long as the effects of the present invention are not impaired, but for example, wet lamination, dry lamination, hot melt lamination, extrusion lamination, coextrusion molding lamination, extrusion coating, photocuring adhesive A laminate, a thermal laminate, etc. are mentioned. Among them, a laminating method using a photo-curing adhesive having a proven record in organic EL device sealing, a hot melt laminate or a thermal laminate having a proven record in solar cells is preferable, and a hot melt laminate or a thermal laminate is a sheet-like sealing material. Is more preferable in that it can be used.

  The heating temperature in the laminate sealing step is usually 130 ° C or higher, preferably 140 ° C or higher, and is usually 180 ° C or lower, preferably 170 ° C or lower. The heating time in the laminate sealing step is usually 10 minutes or longer, preferably 20 minutes or longer, and is usually 100 minutes or shorter, preferably 90 minutes or shorter. The pressure in the laminate sealing step is usually 0.001 MPa or more, preferably 0.01 MPa or more, and usually 0.2 MPa or less, preferably 0.1 MPa or less. By setting the pressure within this range, sealing can be reliably performed, and the sealing materials 5 and 7 from the end can be prevented from protruding or reduced in film thickness due to over-pressurization, thereby ensuring dimensional stability. In addition, what connected two or more solar cell elements 6 in series or in parallel can be manufactured similarly to the above.

[2.13 Applications]
There is no restriction | limiting in the use of the solar cell of this invention, especially the thin film solar cell 14 mentioned above, It can use for arbitrary uses. Examples of fields to which the thin film solar cell of the present invention is applied include solar cells for building materials, solar cells for automobiles, solar cells for interiors, solar cells for railways, solar cells for ships, solar cells for airplanes, solar cells for spacecraft. Batteries, solar cells for home appliances, solar cells for mobile phones, solar cells for toys, and the like.

  The solar cell of the present invention, particularly a thin film solar cell, may be used as it is, or a solar cell may be installed on a substrate and used as a solar cell module. For example, as schematically shown in FIG. 5, a solar cell module 13 provided with a thin film solar cell 14 on a substrate 12 may be prepared and used at a place of use. As a specific example, when a building material plate is used as the base material 12, a solar cell panel can be produced as the solar cell module 13 by providing the thin film solar cell 14 on the surface of the plate material.

  The substrate 12 is a support member that supports the solar cell element 6. Examples of the material for forming the substrate 12 include inorganic materials such as glass, sapphire, or titania; polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyimide, nylon, polystyrene, polyvinyl alcohol, ethylene vinyl alcohol copolymer, Organic materials such as fluororesin, vinyl chloride, polyethylene, cellulose, polyvinylidene chloride, aramid, polyphenylene sulfide, polyurethane, polycarbonate, polyarylate, or polynorbornene; paper materials such as paper or synthetic paper; stainless steel, titanium, aluminum, etc. Or a composite material such as a metal such as stainless steel, titanium, or aluminum whose surface is coated or laminated in order to impart insulation. That.

  In addition, 1 type may be used for the material of a base material, and 2 or more types may be used together by arbitrary combinations and a ratio. Moreover, carbon fiber may be included in these organic materials or paper materials to reinforce the mechanical strength. When the example of the base material 12 is given, Alpolic (registered trademark; manufactured by Mitsubishi Plastics) and the like may be mentioned.

  Although there is no restriction | limiting in the shape of the base material 12, Usually, a board | plate material is used. Moreover, what is necessary is just to set the material of the base material 12, a dimension, etc. arbitrarily according to the use environment. This solar cell panel can be installed on the outer wall of a building.

  EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited to description of a following example.

[Synthesis Example 1: Synthesis of benzodipyrrole compound P1]

  2,3,6,7-tetraphenylbenzo [1,2-b: 4,5-b '] dipyrrole (compound E1) A. Kinsley, S.M. G. P. Plants. J. et al. Chem. Soc. , 1958, 1-7.

A mixture of compound E1 (2.76 g, 6.00 mmol) and iodobenzene (3.21 mL, 28.8 mmol) was suspended in toluene (70 mL), and then argon gas was bubbled through the reaction solution for 10 minutes. To this suspension was added t-butoxy sodium (2.31 g, 24.0 mmol), tri-t-butylphosphine (1.0 M toluene solution, 0.68 mL, 0.68 mmol), and tris (dibenzylideneacetone) (chloroform). ) Dipalladium (0) (648 mg, 0.63 mmol) was added and stirred at reflux for 36 hours. Thereafter, the reaction solution was cooled to room temperature, and the precipitate was collected by filtration. The obtained pale green solid was washed with chloroform and water and then dried to obtain Compound P1 (2.58 g, 4.21 mmol) as a pale yellow solid (yield 70%). The compound P1 was identified by ¹ H NMR, ¹³ C NMR, mass spectrometry, and elemental analysis.

1,2,3,5,6,7-hexaphenylbenzo [1,2-b: 4,5-b ′] dipyrrole (compound P1)
¹ H NMR (500 MHz, 1,1,2,2-tetrachloroethane-d ₂ ): δ 7.08-7.09 (m, 10H), 7.15 (t, J = 7.2 Hz, 2H), 7 .23-7.26 (m, 10H), 7.30-7.35 (m, 8H), 7.59 (s, 2H);
¹³ C NMR (126 MHz, 1,1,2,2-tetrachloroethane-d ₂ ): δ 99.0, 116.5, 125.7, 126.4, 126.8, 127.1, 127.7, 128 .2,128.5,129.0,130.3,131.3,132.3,135.6,136.4,138.6,139.0.
Mass spectrum (APCI +): 613 (M + H).
Calcd _{(C 48 H 52 N 2)} : C, 90.16; H, 5.26; N, 4.57. Found: C, 90.13; H, 5.39; N, 4.62.

[Synthesis Example 2: Synthesis of benzodipyrrole compound P23]

A mixture of compound E1 (1.00 g, 2.17 mmol) synthesized in the same manner as in Synthesis Example 1 and sodium hydride (331 mg, 8.68 mmol) was dissolved in tetrahydrofuran (100 mL) and stirred at room temperature for 5 hours. did. 1,3-propane sultone (850 μL, 9.77 mmol) was added to the solution, and the mixture was heated to reflux for 13 hours. The reaction solution was cooled to room temperature and methanol was added to treat the remaining sodium hydride. The precipitate was filtered and washed with chloroform. The obtained crude product was recrystallized twice from a mixed solvent of water / acetone (1/1) to obtain Compound P23 (512 mg, 0.684 mmol) as a colorless solid (yield 32%). Identification was performed by ¹ H NMR, ¹³ C NMR, and mass spectrometry.

¹ H NMR (500 MHz, DMSO-d ₆ ): δ1.00 (quant, J = 7.5 Hz, 4H), 1.31 (t, J = 7.5 Hz, 4H), 3.33 (t, J = 7.5 Hz, 4H), 6.29 (t, J = 7.4 Hz, 2H), 6.43 (t, J = 7.4 Hz, 4H), 6.47 (d, J = 7.4 Hz, 4H) ), 6.51 (d, J = 6.3 Hz, 4H), 6.54-6.60 (m, 6H), 6.91 (s, 2H);
¹³ C NMR (126 MHz, DMSO-d ₆ ): δ 25.58, 42.62, 48.87, 98.17, 113.36, 123.75, 124.72, 125.17, 128.16, 128. 36, 128.51, 129.41, 130.94, 132.11, 133.91, 135.31, 138.18.
Mass spectrometry (APCI-): m / z 703 ([M + H-2Na] ^- ).

[Synthesis Example 3: Synthesis of benzodipyrrole compound P9]

  D. A. Kinsley, S.M. G. P. Plants. J. et al. Chem. Soc. , 1958, 1-7, and the above compound E2 was synthesized. A mixture of compound E2 (223 mg, 0.484 mmol) and iodobenzene (0.162 mL, 1.45 mmol) was suspended in toluene (3 mL), and then argon gas was bubbled through the reaction solution for 10 minutes. To this suspension was added t-butoxy sodium (186 mg, 1.94 mmol), tri-t-butylphosphine (1.0 M toluene solution, 0.0968 mL, 0.0968 mmol), and tris (dibenzylideneacetone) (chloroform) Palladium (0) (25.1 mg, 0.0242 mmol) was added, and the mixture was stirred at reflux for 20 hours. Thereafter, the reaction solution was cooled to room temperature, and the precipitate was collected by filtration. The obtained light green solid was washed with chloroform and water and then dried to obtain compound P9 (111 mg, 0.181 mmol) as a white solid (yield 37%). Compound P9 was identified by mass spectrometry and elemental analysis.

Mass spectrometry (APCI +): 614 (M + 1).
Calcd _{(C 48 H 52 N 2)} : C, 90.16; H, 5.26; N, 4.57. Found: C, 90.25; H, 5.35; N, 4.44.

[Example 1: Production and evaluation of thin film laminated photoelectric conversion element]
The photoelectric conversion element according to the second embodiment shown in FIG. 2 was produced by the following method. First, an indium tin oxide (ITO) transparent conductive film was deposited at 145 nm on a glass substrate (substrate 101) (sheet resistance 8.4Ω). Then, the anode 102 was formed by patterning the transparent conductive film into a stripe having a width of 2 mm using a normal photolithography technique and hydrochloric acid etching. After the glass substrate on which the anode 102 of the ITO transparent conductive film is thus formed is cleaned in the order of ultrasonic cleaning using a surfactant, water cleaning using ultra pure water, and ultrasonic cleaning using ultra pure water. Then, it was dried by nitrogen blowing, and finally ultraviolet ozone cleaning was performed.

The glass substrate on which the anode 102 was formed was placed in a vacuum vapor deposition apparatus, and the benzodipyrrole compound P1, vanadium pentoxide, and titanyl phthalocyanine (obtained in Synthesis Example 1) were placed on a metal boat disposed in the vacuum vapor deposition apparatus. TiOPc) was added separately. After performing rough evacuation from the vacuum vapor deposition apparatus using an oil rotary pump, it was evacuated using a cryopump until the degree of vacuum in the vacuum vapor deposition apparatus became 2.5 × 10 ⁻⁴ Pa. Thereafter, the metal boats containing the benzodipyrrole compound P1 and vanadium pentoxide were heated, and the benzodipyrrole compound P1 and vanadium pentoxide were co-deposited on the anode 102. The degree of vacuum during the deposition was 2.5 × 10 ⁻⁴ Pa, and the deposition rates of the benzodipyrrole compound P1 and vanadium pentoxide were 0.01 nm / second and 0.004 nm / second, respectively. Thus, a layer containing 50 mol% of vanadium pentoxide was formed to a thickness of 5 nm. Subsequently, heating of the vanadium pentoxide boat was stopped, and a layer of benzodipyrrole compound P1 was further formed to a thickness of 15 nm in the same manner. Thus, the anode buffer layer 103 was formed.

Next, an active layer (p− layer) 104 a was formed on the anode buffer layer 103. As a material for forming the active layer 104a, titanyl phthalocyanine (TiOPc) was used. A metal boat containing titanyl phthalocyanine installed in a vacuum vapor deposition apparatus was heated to perform vapor deposition in the same manner as the anode buffer layer 103. The degree of vacuum during the deposition was 1.0 × 10 ⁻⁴ Pa, and the deposition rate was 0.15 nm / second. Thus, the active layer 104a was formed with a film thickness of 40 nm.

  Next, an active layer (n− layer) 104b was formed on the active layer 104a. Specifically, first, the substrate on which the active layer 104a was formed was taken out into a nitrogen glove box connected to the vacuum deposition chamber. Then, a toluene solution (0.7% by weight) of a fullerene derivative (PCBM) was applied onto the active layer 104a by spin coating at a spin rotation speed of 1000 rpm to form an active layer 104b containing the fullerene derivative (PCBM). . As described above, the active layer 104 including the active layer (p− layer) 104a and the active layer (n− layer) 104b was formed on the anode buffer layer 103.

Next, the cathode buffer layer 105 was formed on the active layer 104. Specifically, the cathode buffer layer 105 was formed by the following procedure. That is, the substrate 101 on which the active layer 104 was formed was placed again in the vacuum deposition apparatus. Moreover, bathocuproine (BCP) was put into a metal boat arranged in a vacuum deposition apparatus. After rough evacuation from the vacuum deposition apparatus using an oil rotary pump, evacuation was performed using a cryopump until the degree of vacuum in the vacuum deposition apparatus was 1.8 × 10 ⁻⁴ Pa. Thereafter, the metal boat containing BCP was heated to deposit BCP on the active layer 104. The degree of vacuum during deposition was 1.7 × 10 ⁻⁴ Pa, and the deposition rate was 0.1 nm / second. Thus, the cathode buffer layer 105 made of BCP was formed on the active layer 104. The film thickness of the cathode buffer layer 105 was 6 nm.

Next, the cathode 106 was formed on the cathode buffer layer 105. Specifically, the cathode 106 was formed by the following procedure. That is, a stripe shadow mask having a width of 2 mm was adhered onto the cathode buffer layer 105 so as to be orthogonal to the ITO stripe of the anode 102. This shadow mask is used as a mask for forming the cathode 106. And the board | substrate 101 with which the mask was arrange | positioned was arrange | positioned in a vacuum evaporation system, and it exhausted until the vacuum degree in a vacuum evaporation system became 2.6 * 10 <^-4> Pa. Then, aluminum was deposited on the cathode buffer layer 105. The degree of vacuum during deposition was 2.6 × 10 ⁻⁴ Pa, and the deposition rate was 0.5 nm / second. Thus, a cathode 106 containing aluminum was formed. The film thickness of the cathode 106 was 80 nm.

    The laminate including the substrate 101, the anode 102, the anode buffer layer 103, the active layer 104, the cathode buffer layer 105, and the cathode 106 obtained as described above is placed in a nitrogen glove box, and the back glass is placed on the cathode 106 side. A laminated body was sealed by arranging a plate and bonding the back glass plate and the substrate 101 together using a photo-curing resin. As described above, a photoelectric conversion element having a light receiving area portion having a size of 2 mm × 2 mm was produced.

The photoelectric conversion element produced as described above was irradiated with light from a solar simulator (AM1.5G) at an irradiation intensity of 100 mW / cm ² to measure voltage-current characteristics. As a result, the open circuit voltage (Voc) was 0.62 V, the short circuit current (Jsc) was 11.2 mA / cm ² , the fill factor (FF) was 0.38, and the energy conversion efficiency (PCE) was 2.7%. .

[Comparative Example 1]
A device was fabricated in the same manner as in Example 1 except that PEDOT: PSS (poly (3,4-ethylenedioxythiophene) -poly (styrenesulfonic acid)) which is a conductive polymer was used for the anode buffer layer 103. . Specifically, in Comparative Example 1, the anode buffer layer 103 was produced as follows. First, PEDOT: PSS (product name CLEVIOS ^™ AI 4083, manufactured by Stark Vitec Co., Ltd.) was spin-coated on the anode 102 at a rotational speed of 1500 rpm. Then, the anode buffer layer 103 containing PEDOT: PSS was formed by heat-drying for 10 minutes at 120 degreeC in air | atmosphere, and also heat-processing for 3 minutes at 180 degreeC in nitrogen. The thickness of the anode buffer layer 103 was 30 nm.

The photoelectric conversion element thus fabricated was irradiated with light from a solar simulator (AM1.5G) at an irradiation intensity of 100 mW / cm ² to measure voltage-current characteristics. As a result, the open circuit voltage (Voc) was 0.66 V, the short circuit current (Jsc) was 9.6 mA / cm ² , the fill factor (FF) was 0.31, and the energy conversion efficiency (PCE) was 2.0%. .

[Example 2: Production and evaluation of bulk hetero photoelectric conversion element]
The photoelectric conversion element according to the first embodiment shown in FIG. 1 was produced by the following method. The substrate 101 was the same as that in Example 1, and the anode 102 was formed in the same manner as in Example 1. Thereafter, the substrate was cleaned in the same manner as in Example 1.

The anode buffer layer 103 was formed by vacuum deposition in the same manner as in Example 1 except that the benzodipyrrole compound P9 was used instead of the benzodipyrrole compound P1. The degree of vacuum during the deposition was 1.5 × 10 ⁻⁴ Pa, and the deposition rates of the benzodipyrrole compound P9 and vanadium pentoxide were 0.04 nm / second and 0.02 nm / second, respectively. Similarly to Example 1, a layer containing 50 mol% of vanadium pentoxide was formed to a thickness of 5 nm, and a layer of benzodipyrrole compound P9 was formed to a thickness of 15 nm.

  Next, the substrate on which the anode buffer layer 103 was formed was placed in a nitrogen glove box, and the active layer 104 was formed on the anode buffer layer 103. The active layer 104 was formed as follows. First, an ODCB (orthodichlorobenzene) solution containing 1% by weight of P3HT (regioregular poly (3-hexylthiophene)) as an electron donor and PCBM as an electron acceptor was prepared as a coating solution. Then, this coating solution was spin-coated on the anode buffer layer 103 at a rotation speed of 600 rpm. After application, the active layer 104 was formed by performing a drying process at 70 ° C. for 10 minutes.

  Thereafter, an aluminum cathode 106 was deposited on the active layer 104 in the same manner as in Example 1. After vapor deposition, heat treatment was performed at 120 ° C. for 10 minutes in a glove box. Furthermore, the photoelectric conversion element was produced by sealing similarly to Example 1. FIG.

The photoelectric conversion element thus fabricated was irradiated with light from a solar simulator (AM1.5G) at an irradiation intensity of 100 mW / cm ² to measure voltage-current characteristics. As a result, the open circuit voltage (Voc) was 0.33 V, the short circuit current (Jsc) was 5.8 mA / cm ² , the fill factor (FF) was 0.38, and the energy conversion efficiency (PCE) was 0.7%. .

[Comparative Example 2]
A device was fabricated in the same manner as in Example 2 except that PEDOT: PSS, which is a conductive polymer, was used for the anode buffer layer 103. Specifically, the anode buffer layer 103 was produced in the same manner as in Comparative Example 1.

The photoelectric conversion element thus fabricated was irradiated with light from a solar simulator (AM1.5G) at an irradiation intensity of 100 mW / cm ² to measure voltage-current characteristics. As a result, the open circuit voltage (Voc) was 0.39 V, the short circuit current (Jsc) was 6.2 mA / cm ² , the fill factor (FF) was 0.19, and the energy conversion efficiency (PCE) was 0.5%. . The current-voltage characteristic had a shape bent in an S shape.

[Example 3: Production and evaluation of thin film laminated photoelectric conversion element having i-layer]
The photoelectric conversion element according to the third embodiment shown in FIG. 3 was produced by the following method. The substrate 101 was the same as that in Example 1, and the anode 102 was formed in the same manner as in Example 1. Thereafter, the substrate was cleaned in the same manner as in Example 1.

  The anode buffer layer 103 was produced as follows. First, using a water / acetone (1/1) mixed solvent as a solvent, 0.5% by weight of the benzodipyrrole compound P23 obtained in Synthesis Example 2 and 50 mol% of p with respect to the benzodipyrrole compound P23. -A coating solution containing toluenesulfonic acid was prepared. This coating solution was spin-coated on the anode 102 at a rotational speed of 3000 rpm. The substrate after coating was heat-dried at 120 ° C. for 10 minutes in the atmosphere, and further heat-treated at 180 ° C. for 10 minutes in nitrogen, whereby the anode buffer layer 103 containing the benzodipyrrole compound P23 and p-toluenesulfonic acid was formed. Formed. The thickness of the anode buffer layer 103 was 20 nm.

  Next, an active layer (p− layer) 104 a was formed on the anode buffer layer 103. Specifically, the active layer 104a was formed by the following procedure. That is, a coating solution was prepared by dissolving 0.5 wt% of compound CP-1 which is a precursor of a tetrabenzoporphyrin compound in a mixed solvent of chlorobenzene and chloroform (weight ratio 2: 1). Then, this coating solution was applied onto the anode buffer layer 103 by spin coating at a rotation speed of 1500 rpm. After the application, heat treatment was performed on a hot plate at 180 ° C. for 20 minutes. By this heat treatment, the brown precursor film is converted into a film of green tetrabenzoporphyrin (compound BP-1). Thus, a crystalline active layer (p-layer) 104a containing tetrabenzoporphyrin (compound BP-1) was formed. The average film thickness of the active layer 104a was 25 nm. Compound CP-1 (1,4,8,11,15,18,22,25-octahydro-1,4: 8,11: 15, 18: 22,25-tetraethano-29H, 31H-tetrabenzo [b, g , L, q] porphyrin) was synthesized with reference to the method described in JP-A No. 2003-304014.

  Next, an active layer (i-layer) 104c was formed on the active layer 104a. Specifically, the active layer 104b was formed by the following procedure. That is, a coating solution was prepared by dissolving 0.6% by weight of compound CP-1 and 0.8% by weight of fullerene derivative SIMEF2 in a mixed solvent of chlorobenzene and chloroform (weight ratio 1: 1). Then, this coating solution was applied onto the active layer 104a by spin coating at a rotation speed of 1500 rpm. After application, heat treatment was performed at 180 ° C. for 20 minutes. By this heat treatment, compound CP-1 is converted to compound BP-1. Thus, an active layer (i-layer) 104c containing tetrabenzoporphyrin (compound BP-1) and the fullerene derivative SIMEF2 was formed. Fullerene derivative compound SIMEF2 was synthesized with reference to the method described in JP2011-098906A.

  Next, an active layer (n− layer) 104b was formed on the active layer 104c. Specifically, the active layer 104b was formed by the following procedure. That is, a coating solution in which 0.7% by weight of the fullerene derivative SIMEF2 was dissolved in toluene was prepared. Then, this coating solution was applied onto the active layer 104c by spin coating at 1000 rpm. After application, the active layer (n-layer) 104b containing the fullerene derivative (SIMEF2) was formed by drying at 120 ° C. for 10 minutes.

  As described above, the active layer 104 including the active layer (p-layer) 104a, the active layer (i-layer) 104c, and the active layer (n-layer) 104b was formed on the anode buffer layer 103.

Next, the cathode buffer layer 105 was formed on the active layer 104. Specifically, the cathode buffer layer 105 was formed by the following procedure. That is, the substrate 101 on which the active layer 104 was formed was placed in a vacuum deposition apparatus. Moreover, the phenanthroline compound (NBphen) was put into the metal boat arrange | positioned in a vacuum evaporation system. After rough evacuation from the vacuum deposition apparatus using an oil rotary pump, evacuation was performed using a cryopump until the degree of vacuum in the vacuum deposition apparatus was 2.6 × 10 ⁻⁴ Pa. Thereafter, the metal boat containing NBphen was heated to deposit NBphen on the active layer 104. The degree of vacuum during deposition was 2.6 × 10 ⁻⁴ Pa, and the deposition rate was 0.1 nm / second. Thus, the cathode buffer layer 105 made of NBphen was formed on the active layer 104. The film thickness of the cathode buffer layer 105 was 5 nm.

  Thereafter, an aluminum cathode 106 was deposited on the cathode buffer layer 105 in the same manner as in Example 1, and sealing was performed in the same manner as in Example 1 to produce a photoelectric conversion element.

  The thus produced photoelectric conversion element was irradiated with spectral monochromatic light (450 nm), and voltage-current characteristics were measured. As a result, the external quantum efficiency at this wavelength was 54%. The external quantum efficiency is a value obtained by dividing the number of incident photons of monochromatic light separated by the number of charges of the short-circuit current of the element.

[Comparative Example 3]
A device was fabricated in the same manner as in Example 3 except that PEDOT: PSS which is a conductive polymer was used for the anode buffer layer 103. Specifically, the anode buffer layer 103 was produced in the same manner as in Comparative Example 1.

  The thus produced photoelectric conversion element was irradiated with spectral monochromatic light (450 nm), and voltage-current characteristics were measured. As a result, the external quantum efficiency at this wavelength was 48%.

  As mentioned above, it turned out that the benzodipyrrole compound of this invention can be utilized as a photoelectric conversion element material. In particular, the photoelectric conversion elements of Examples 1 to 3 having the anode buffer layer containing the benzodipyrrole compound of the present invention have an energy conversion efficiency as compared with the case where PEDOT: PSS which is a conventional anode buffer layer material is used. It was found that this is superior.

101 Substrate 102 Electrode 103 Buffer layer 104a Active layer (p-layer)
104b Active layer (n-layer)
104c Active layer (i-layer)
DESCRIPTION OF SYMBOLS 105 Buffer layer 106 Electrode 1 Weatherproof protective film 2 Ultraviolet cut film 3,9 Gas barrier film 4,8 Getter material film 5,7 Sealing material 6 Solar cell element 10 Back sheet 11 Sealing material 12 Base material 13 Solar cell module 14 Thin film Solar cell

Claims (6)

A photoelectric conversion element having a pair of electrodes and an active layer present between the electrodes,
A photoelectric conversion element comprising a layer containing a benzodipyrrole compound represented by the following general formula (I) between the active layer and one of the electrodes.

(In formula (I), ^one of X ¹ and X ² is a nitrogen atom having substituent R ² , the other is a carbon atom having substituent Ar ³ , and R ^{1 to} R ⁴ are each independently 1. A valent organic group, and Ar ^{1 to} Ar ⁴ each independently represents an aromatic group which may have a substituent.)   The photoelectric conversion element according to claim 1, wherein the layer containing the benzodipyrrole compound is provided between an anode that is one of the electrodes and the active layer.   The photoelectric conversion element according to claim 2, wherein the layer containing the benzodipyrrole compound further contains an electron accepting compound.   The photoelectric conversion element according to claim 3, wherein an electron affinity of the electron-accepting compound is 4 eV or more and 7 eV or less.   It is a solar cell, The photoelectric conversion element of any one of Claims 1 thru | or 4 characterized by the above-mentioned.   A solar cell module comprising the photoelectric conversion element according to claim 5.

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